Boiling is used when disinfecting compounds
are not available. It is a good method for killing
disease producing organisms, but has several
1. Fuel is required.
2. It takes a long time for the water to boil
and then to cool.
3. There is no residual protection against
4. The water must be held at a rolling boil for
at least 15 seconds to make it safe for
FIVE-GALLON WATER CANS
Five-gallon cans of water may be disinfected
1. Fill the 5-gallon can with the cleanest water
2. Check iodine tablets for physical change.
3. Dissolve 20 iodine tablets in a canteen cup
full of water. Add this solution to the
5-gallon container and agitate the solution.
4. Place the capon the container loosely; wait
5 minutes, then again agitate the container
5. Tighten the cap and wait an additional 20
minutes before using the water for any
Small Unit Water Treatment
When treated water is not available, small
groups of personnel can treat an emergency water
supply by chlorinating water in a Lyster Bag.
Lyster Bags are 36-gallon containers issued to
units on the basis on one bag per 100 men. The
porous canvas, of which the bags are made, allows
seepage of water and thus cooling by evaporation.
Unfortunately, the canvas is organic matter
that has a chlorine demand of its own and makes
it difficult to maintain adequate levels of chlorine.
The bag is suspended from ropes or poles. Sagging
can cause the outlets at the bottom of the bag to
drop onto the ground below the bag. Should this
occur, the rope should be adjusted so that the
cover will again fit snugly around the upper part
of the bag and the spigots will be at least 18 inches
above ground level. Proper adjustment of the
cover prevents contamination of the water by
dust, dirt, and insects. The bag must be inspected
frequently for cleanliness and chlorine residual.
If the bags are dirty, they should be scrubbed with
water, disinfected, and thoroughly rinsed.
1. Fill the bag with the clearest water
2. Initially take 2 ampules of 65 to 70 percent
calcium hypochloride (HTH) and pour the
contents into a canteen cup. Add approx-
imately 4 to 6 ounces of water to the cup
and stir the solution thoroughly. Allow the
solution to settle for several minutes (ap-
proximately 5 minutes) so the insoluble
portion will settle to the bottom of the cup.
Then stir the clear, supernatant liquid into
the Lyster Bag.
3. Flush the faucets; wait 10 minutes, and col-
lect the water sample. If it is less than a 5.0
ppm free available chlorine residual, repeat
step 2 above.
4. Continue repeating the disinfection pro-
cedure until a 5.0 ppm residual is obtained
after 30 minutes of contact time. The water
is ready for use.
WATER SUPPLY AFLOAT
Potable water for shipboard use comes either
from the sea through the ships evaporators, from
another ship, or from sources ashore. The ships
medical department is responsible for determin-
ing the quality of the water; the engineering sec-
tion determines the quantity stored or produced
and does the actual chlorination or bromination.
Free Available Chlorine (FAC)
Potable water obtained from an area where
amebiasis or hepatitis is endemic must be
chlorinated or brominated to obtain a 2.0 ppm
residual in the tanks following a 30-minute con-
Water obtained from an approved source or
distilled in open seas must be chlorinated to 0.2
ppm following a 30-minute contact period.
The free available chlorine level of a ships
water supply is checked by the Palin-DPD
method. With this method, a tablet is placed in
a small test tube filled with water. If chlorine (or
bromine for ships having bromine disinfection)
is present in the water, a color change will take
place as the tablet dissolves. When the tablet is
fully dissolved, the color of the sample is com-
pared to color standards furnished with the kit.
When a color match is obtained, the disinfectant